ICEM11 Final Program 9.7.11pm_ICEM07 Final Program ... - Events

Session 9 Abstracts
7) A NUMERICAL INTERPRETATION OF DENSITY HOMOGENIZATION
OF BENTONITE MATERIAL IN WETTING PROCESS (wP-59153)
Atsushi Iizuka, Yusuke Takayama, Katsuyuki Kawai, Kobe University; Shinya Tachibana, Saitama University;
Shintaro Ohno, Ichizo Kobayashi, Kajima Corporation (Japan)
The bentonite material is expected to be a buffer in the nuclear waste disposal, since it has low permeability and excellent
expansion characteristics. Its expansion characteristics through wetting process can be interpreted based on the full saturation line
that is depicted as a unique line on the density and the confining pressure relationship (Kobayashi et. al., 2007). And its elasto-plastic
constitutive relation can be formulated by introducing additional irreversible strain component describing the expansion of
montmorillonite contained in the bentonite material. Its constitutive model can express the mechanical behavior of compacted bentonite
material consistently in the unsaturated sate up to fully saturated state. Then, this paper describes the density homogenization
process through a series of soil-water coupled elasto-plastic finite element simulations. Namely, we consider the cases that the
bentonite composed of two specimens having different initial densities is permeated with the constant water head. Stresses and
strains developing in the bentonite, particularly the density change of bentonite, are examined. According to a series of numerical
simulations, the density of bentonite composed of two specimens having different initial densities is not homogenized into a certain
unique value of density when the bentonite reaches fully saturated state. To confirm the simulation results, we carried out a
series of experiments. The experiment results also support our simulation results.
8) COMPARISON OF ORGANIC AND INORGANIC ION EXCHANGERS FOR THE TREATMENT OF
RADIOACTIVE LIQUID WASTES BY ION EXCHANGE PROCESSES (w/oP-59107)
Yves Barre, CEA (France)
There are number of liquid processes and wastes streams at nuclear facilities that require treatment for process chemistry control
reasons and/or the removal of radioactive contaminants. One of the most common treatment methods for such aqueous streams
is the use of ion exchange, which is a well developed technique that has been employed for many years in the nuclear industries.
Nuclear power plant process water systems have typically used organic ion exchange resins to control system chemistry to minimize
corrosion and to remove radioactive contaminant. In the past decade, inorganic ion exchange materials have emerged as an
increasingly important replacement or complement for conventional organic ion exchange resins, particularly in liquid radioactive
waste treatment and spent fuel reprocessing applications. Inorganic ion exchangers often have the advantage of a much greater
selectivity than organic resins for certain important radionuclides such as 137Cs and 90Sr. These inorganic materials have also
advantages with respect to immobilization and final disposal when compared with organic ion exchangers.
Fixed bed column experiments were carried out with porous titanium dioxide beads and with standard polystyrene divinylbenzene
resin in order to estimate the dynamics of 90Sr decontamination from a simulated liquid wastes. We present a comparison of
the kinetic and thermodynamics sorption properties between organic and inorganic ion exchangers.
9) DETRITIATION OF JET PLASMA FACING COMPONENTS (w/oP-59345)
Pierre Trabuc, Karine Liger, Nicolas Ghirelli, Christophe Perrais, CEA (France)
Beryllium tiles are proposed for ITER and the ITER-like JET wall project. The development of detritiation / recycling methods
for bulk Be and the definition of a strategy, is necessary to reduce the final waste and the constraints linked to the management
of mixed Be waste.
The tritium content in Be is the results of contribution of different mechanisms (activation, trapping in defects due to neutron
flux, and diffusion in the bulk). In fusion machines, it is foreseen to remove a part of this tritium first with in-situ detritiation techniques,
but also with ex-vessel detritiation methods. Among these methods, thermal desorption is a good candidate.
In this paper, the efficiency of thermal desorption of trapped tritium using different carrier gases is assessed. Effect of oxidant
and reductive gases on detritation of flakes (~20 GBq/g), limiter (~103Bq/g) and divertor (~104Bq/g) tiles, at relatively high temperature
(800°C), is experimentally analysed. Best results were obtained under N2 +20%O2 , after 10 h at 800°C (during 2 days) and
5 hours at 1050°C (during one day). With this treatment, it is possible to conclude that flakes, limiter and divertor tiles are allowed
as Low Level Waste (between 0.4 Bq/g and 12 kBq/g).
10) EXPERIMENTAL DROP TESTING OF WASTE CONTAINERS FOR THE KONRAD REPOSITORY (w/oP-59269)
Tino Neumeyer, Karsten Müller, Holger Voelzke, Federal Institute for Materials Research and Testing (BAM) (Germany)
The Konrad repository for not heat generating radioactive wastes was licensed in 2002 primarily. Due to legal actions the final
confirmation of this license took place not until 2007. Subsequently, the Federal Office for Radiation Protection (BfS) began scheduling
backfitting of the former iron ore mine into a repository. The licensed repository volume is 303,000 m3 considering estimations
of expected waste volumes to be disposed off. The mine itself would offer a much larger volume. Waste packages can be disposed
off as recently as the repository is ready for operation what is expected not before the end of this decade. Nevertheless, there
is high interest of qualified and certified waste conditioning and packaging for disposal today, what for from BAM and BfS tested,
evaluated and certified containers are needed.
In recent years numerous container prototypes made of steel, concrete and ductile cast iron have been tested by BAM, the Federal
Institute for Materials Research and Testing in Germany. To cover the Konrad test requirements in a conservative manner container
drop tests are performed mostly onto the unyielding IAEA target of BAMs large drop test facility instead of a representative
foundation of the repository.
This conference contribution focuses on experimental drop…
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